The present invention relates to an apparatus for handling palletized piles of sheet-shaped materials, especially by the admission or removal of the pile to or from a production machine, e.g. for printing, pressing or punching of the materials, which apparatus comprises means for controlling the functions of the apparatus, a fork tower having two sets of mutually movable forks for holding and inverting the pile and being swingable between a substantially vertical and a substantially horizontal position.
Today's production machines for handling sheets within the graphic arts industry are highly developed machines where the raw material, viz. sheets of paper or board, is fed to the machine as palletized sheet pile. Normally, the machines are provided with an automatic feeding device that permits the contents of the pallet to be used up without stopping the machine. When the feeding pallet, i.e., the pallet used in the admission of sheets, is empty, the machine is stopped and a new pallet is placed in position in relation to the feeding device of the machine. This involves a period of rearrangement which may typically be in the order of 10 minutes. However, most modern production machines are constructed so that they may continue the production substantially uninterrupted, provided a new palletized sheet pile is in position in relation to the feeding device and in a ready-to-use condition.
The following conditions have to be fulfilled before a palletized pile of sheets can be fed automatically into the production machine: the pallet should be oriented correctly so that the sheets are fed in the right direction, all the sheets should be piled uniformly oriented, all the sheets should be aerated immediately before admittance into the production machine, the pile should be aligned, the pile should be placed accurately in relation to the feeding device, and the pile should be provided with machine pallets or supporting plates which are designed specifically for the production machine.
U.S. Pat. No. 3,670,903 discloses an apparatus which makes it possible to fulfill some of these conditions in a manual and semi-automatic handling of the pile. The apparatus comprises a fork tower with two sets of mutually movable forks. The apparatus is intended for gripping a pile, inverting the same, and then in turn placing the pile upside down. Moreover, the apparatus comprises controlling means which consist of electrical buttons for energizing and deenergizing a motor effecting a tilting of the pile only. Thus an operator has to decide when to start and stop the motion of the movable part. Accordingly, this apparatus is associated with disadvantages as it necessitates time-consuming manual handlings between this apparatus and further auxiliary equipment which is necessary to prepare the pile for use in a production machine. Furthermore, stops in the supply to the production machine will also occur each time a new pile is to be inverted.
Similar handling problems exist when removing a palletized pile from a production machine. In principle the individual steps for removing the pile take place in reverse order as the pile which is produced at the outlet of a production machine most often has to go through a succeeding treatment and the steps up to and including the preparing of the pile for introduction into a following production machine may thus be substantially identical with the corresponding steps for the admission of a pile to the first production machine.
It is the object of the present invention to provide an apparatus wherein the above-mentioned drawbacks are remedied and which simultaneously enables a continuous accomplishment of the sequence of operations for preparing a pile and which simultaneously delivers the pile in a correct position and at the correct moment so that stops are eliminated.